Influence of gastric bypass surgery on resting energy expenditure, body composition, physical activity, and thyroid hormones in morbidly obese patients

Abstract

Introduction

One way to lose weight is bariatric surgery. Various studies have shown that after Roux-en-Y gastric bypass (RYGB), resting energy expenditure (REE) decreased may be a result of changes in fat-free mass (FFM) and thyroid-stimulating hormone levels. The aim of our study was to assess changes in body composition, REE, and thyroid hormones in patients undergoing RYGB.

Methods

A total of 42 patients participated (21 undergoing RYGB and 21 age- and weight-matched subjects as controls) in our study. Weight, body-mass index, body composition, resting metabolic rate, physical activity, and thyroid hormones were measured at baseline in cases and 3 months after surgery in case and control groups.

Results

At 3 months after surgery, patients lost an average of 21.7±1.4 kg weight, and fat mass, FFM, and REE decreased significantly. REE was higher in cases compared to controls. T₄, T₃, and thyroid-stimulating hormone at 3 months after RYGB decreased, but the decrease was significant only in T₄ compared to controls. FFM was higher and fat mass lower in cases compared to controls.

Conclusion

We detected a meaningful difference in REE before and after surgery, but we did not detect any meaningful difference in REE between controls and cases.

Keywords:

• gastric bypass surgery
• resting energy expenditure
• body composition

Acknowledgments

This study was supported by Tehran University of Medical Sciences (grant EC_00299).

Disclosure

The authors report no conflicts of interest in this work.